I have two pumps connected to my pond. One is a pondmaster 18 and the other is a mag 7 (I think). They were doing fine on the same outlet until recently. The breaker for that gfci kept tripping. If I plug the pondmaster 18 by itself it works fine. When I plug the mag 7 it begins to pump, but trips the breaker in about 20 seconds. Is the mag 7 bad even though it is still pumping? I use it for the fountain which is about 6 feet tall.